Directional Drilling
Directional Drilling
Directional Drilling
DIRECTIONAL DRILLING
Directional drilling is defined as an art and science
involving deflection of a well bore in a specified
direction in order to reach a predetermined object
below the surface of the earth.
INACCESSIBLE LOCATIONS
If reservoir located under river beds, mountains,
cities etc, this technique of directional drilling is
used .
SOURCE: T.A.INGLIS
HORIZONTAL WELL
Horizontal well may be defined as an extension of highly deviated wells,
drilled in order to situate a drain of considerable length at a precise depth
in a reservoir with an angle of inclination approaching 90o from vertical.
Advantages:
1.Increasing the drainage area.
2.Prevention of gas coning or water coning problems.
3.Increased penetration of the producing formation.
4.Increasing the efficiency of enhanced oil recovery ( EOR ).
5.Improving productivity in fractured reservoirs by intersecting a numbers
of vertical fractures.
ERD WELL
In these well departure of the well is twice or more of TVD.
This separates it from conventional directional
wells.Advantages:
Increased horizontal displacement from central platform.
1. Increased penetration length of reservoir.
2. Require less number of wells to develop a field.
3. Require less number of platforms to develop a field in
offshore.
Multilateral Drilling
Multilateral well has been defined as a well that has
more than one horizontal or near horizontal laterals
drilled from single site and connected back to a single
well bore.
Applications:
. Greater reservoir exposure.
Drain more than one reservoir.
Exploit irregular reservoirs efficiently.
Speed up reservoir drainage.
Reduction in drilling cost per unit length of the
well bore contacting, the reservoir rock.
Ability to obtain a given length of horizontal well
bore in reservoir where drag would perhaps limit
the length of single horizontal well bore.
Reduction in number of slots and thus the
number of production platforms.
B. CONSTRUCTION INDUSTRY
A small diameter pilot hole is drilled in a smooth arc
beneath the river until it immerges on the other side.
This acts as a guide for the large diameter pipe
forming the conduit.
The hole is drilled through soft sediments about 40
below the river bed. This techniques has been used
to cross rivers up to 200 wide.
2
HD / TVD
1
IN THE PRESENT WORLD WIDE SCENARIO WHEN HORIZONTAL
DEPARTURE HAS CROSSED THE BARRIER OF 10 KMS. (10,728 M),
MD 11,278 M AT TVD OF 1,637 M ONLY THE DEFINITIONS ARE
REDEFINED AS BELOW:
REACH / TVD
<
CONVENTIONAL DIRECTIONAL
DRILLING (NON ERD)
REACH / TVD
= 2 3 EXTENDED REACH DRILLING
REACH / TVD
> 3
SEVERE EXTENDED REACH
DRILLING
80o
60
70o
10000(3050 M)
10000
INLINATION
(degree)
20000
(3050 M)
(5020 M)
HORIZONTAL REACH
(m)
30000
(9150 M)
DRAINGE AREA
(km2
60
3050
5.31
70
5020
11.9
80
9150
44.26
200
10000(3050 M)
A
C
PENETRATION THEOUGH PAY
ZONE (TRUE VERTICAL
THICKNESS = 60 m/200)
CURVE
INLINATION
(degree)
60
120 m/400
70
180 m/585
80
352 m/1151